simulant

/S IH1 M Y AH0 L AH0 N T/
noun
  1. 1

    Something that simulates something else such as, for example, a gemstone.

    โ€œDue to its low cost and close visual likeness to diamond, cubic zirconia has remained the most gemologically and economically important diamond simulant since 1976.โ€

adjective
  1. 1

    Simulating, replacing, or having the form or appearance of something else.

Source: https://en.wiktionary.org/wiki/simulant